An assembly is provided that includes a slider seal having a washer and a tubular puck. The washer includes an inner washer surface and an outer washer surface. The inner washer surface extends around an axis of the slider seal and has a non-circular cross-sectional geometry. The inner washer surface forms a washer bore axially through the washer. The outer washer surface extends around the axis and has a cross-sectional geometry with a shape that is different than a shape of the non-circular cross-sectional geometry. The tubular puck projects axially through the washer bore and includes an outer puck surface. The outer puck surface extends around the axis. The outer puck surface is sealingly engaged with and configured to slide axially along the inner washer surface.